PHP Extension

Get an S/MIME Signing Time

Demonstrates the Chilkat Mime.GetSignatureSigningTimeStr method, which returns the CMS signingTime attribute for the signer at a zero-based index, as an RFC 822-style date string in GMT. The only argument is the signer index.

Note: The file paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: This is the timestamp the signer asserted at signing — useful for "when was this signed" audit trails and for evaluating whether the signing certificate was valid at that moment. Because it is a signed attribute, it is tamper-evident. Guard the call with HasSignatureSigningTime, since the attribute is optional. Note it is the signer's claim, not a trusted third-party timestamp.

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<?php

include("chilkat.php");

$success = false;

$mime = new CkMime();
$success = $mime->LoadMimeFile('qa_data/signed.eml');
if ($success == false) {
    print $mime->lastErrorText() . "\n";
    exit;
}

//  After verifying, get the CMS signingTime for each signer that has one, as an RFC 822 date string
//  in GMT.  The only argument is the zero-based signer index.
$success = $mime->Verify();
if ($success != true) {
    print $mime->lastErrorText() . "\n";
    exit;
}

$n = $mime->get_NumSignerCerts();

for ($i = 0; $i <= $n - 1; $i++) {
    //  Only signers that included a signing time have one to retrieve.
    if ($mime->HasSignatureSigningTime($i)) {
        $signingTime = $mime->getSignatureSigningTimeStr($i);
        if ($mime->get_LastMethodSuccess() == false) {
            print $mime->lastErrorText() . "\n";
            exit;
        }

        print 'Signer ' . $i . ' signing time: ' . $signingTime . "\n";
    }

}


?>